Hypothermia and mortality and morbidity. An epidemiological analysis.

Department of Community Medicine and Epidemiology, University College, Dublin 2, Republic of Ireland.

Abstract

STUDY OBJECTIVE--The aim was to identify socioeconomic variables associated with deaths and hospital admissions due to hypothermia
and to quantify the risk due to ambient outside temperature. DESIGN--The study was a survey of deaths and hospital admissions
due to hypothermia (ICD 991.6), for the period 1979-85 inclusive, identified from death certificates and Hospital Inpatient
Enquiry (HIPE) data. SETTING--The study included all deaths and hospital admissions due to hypothermia (1979-85) in the 26
counties of the Republic of Ireland, population 3.5 million. SUBJECTS--All deaths coded during the study period as being due
to hypothermia and all persons admitted to hospital during the study period for whom hypothermia was recorded as a discharge
diagnosis in HIPE data. MEASUREMENTS AND MAIN RESULTS--Demographic data and date of death/diagnosis were obtained from both
data sets. Complete national temperature records were obtained from the meteorological service and a temperature was assigned
to each case representing ambient outside temperature at which hypothermia developed. Risk of hypothermia at a given temperature
was obtained by dividing the number of cases at that temperature by the appropriate person-years of exposure of the entire
national population. Incidence of and mortality from hypothermia doubled with each 5 degrees C and 4 degrees C fall in temperature
respectively; the majority of deaths and hospital admissions occurred between October and March. Incidence and mortality increased
with age and men had 30% higher case fatality than women. Single men had four times the incidence and 6.5 times the mortality,
and single women had double the incidence and four times the mortality of married men and women respectively. Low population
density was also an important risk marker. CONCLUSIONS--The risk of hypothermia due to ambient outside temperature has been
quantified and a high risk group was identified. A combination of statutory support measures and good neighbourliness could
prevent illness and deaths from hypothermia.